Lighting systems for areal illumination typically comprise (1) a set of “luminaires” (light fixtures comprising mounting hardware and one or more light-emitting elements such as incandescent or fluorescent bulbs or arrays of light-emitting diodes [LEDs]), together with (2) one or more sensor elements (motion sensors, light sensors, and the like), (3) control devices (such as dimmers and switches), and (4) power drivers to set the output light level of each luminaire as a function of sensor outputs and control device settings. Such systems can range in complexity from a single wall switch and bulb to commercial building lighting systems comprising hundreds of luminaires, sensors, and control devices.
A common way to specify, configure, and install such systems requires the use of discrete components, where each of the above elements are purchased separately, and the control logic is implemented by the way the components are connected together using wired or wireless connections. Where convenient, certain elements can be physically grouped. For example, an outdoor security light fixture can have a motion sensor built into the fixture, or a table lamp can have an on/off switch built in. Often, however, such combinations are not used, and each element is separately purchased, installed, and wired together in order to create functional groups.
As the total number of components increases, there can be a need for more sophisticated control systems. These are typically implemented using electronic control systems, which can be implemented using either custom electronics or software running on a more general-purpose control device such as a digital computer. Such systems require a trained engineer to manually connect all devices, describe the system to the control hardware and software, and to define the control functions to be implemented.
The cost of discrete components as well as the cost of installation and programming labor have thus far inhibited wide-spread adoption of sophisticated control systems. There are, nevertheless, obvious cost savings and performance benefits that can be realized by intelligently managing the on-time and on-intensity of each light source within lighting systems. Potential saving in electricity usage can be large, and safety and security can be enhanced. Nevertheless, to be widely adopted, the components need to be inexpensive, the installation should be quick and easy, and all configuration work should be possible within the skill range of an average commercial electrician or that of building maintenance personnel.
In order to reduce installation and commissioning costs as well as the skill level required to implement these tasks, it is possible to automate some of the commissioning steps. For example, co-owned and co-pending U.S. patent application Ser. No. 12/538,806 which is incorporated herein by reference, discloses methods for auto-commissioning a lighting system by using signal sources and sensors built into each fixture to automatically determine proximity of fixtures to each other and to automatically create logical groups. However, whether or not such auto-commissioning is used, in many cases, further refinements must be manually implemented. An example of such manual commissioning is disclosed in co-owned and co-pending U.S. patent application Ser. No. 12/708,460 which is also incorporated herein by reference.
Radio Frequency Identification (RFID) is used in a variety of applications as a means of providing unique identification codes associated with a set of related items. These items may range from products in a store to pallets in a warehouse, persons in a race, pets, racehorses, farm animals, cars passing a tollbooth or entering a parking lot, etc. Typically, individual RFID “tags” are attached to each item where each tag comprises a “chip” encoding digital identification data and an antenna that can communicate wirelessly to an RFID “reader.” Most embodiments use “passive” tags, where the power necessary to receive a query and transmit identification data back to the reader is also provided via the wireless connection. Some embodiments use “active” tags which incorporate batteries to provide a higher power signal that can be read from greater distances. RFID systems have been implemented over a wide range of radio frequencies. Common embodiments exist using frequencies near 100 kHz, 10 MHz, and various UHF frequencies (100s of MHz to a few GHz). The choice of frequencies is dictated in part by available radio bands not designated for other applications and in part by the performance needs of particular applications. Each frequency band provides different performance and price characteristics.